This invention relates to synchronizers for power transmissions and, more particularly, to synchronizer controls for multiple speed planetary transmissions.
Manual transmissions have been employed in passenger vehicles and trucks for many years. Manual transmissions have a central shaft and a countershaft, as well as an input head gearset. A plurality of ratio gears disposed in meshing relationship are rotatably mounted on at least one of the main shaft or countershaft and connectible selectively and individually with the other of the two shafts through a synchronizer clutch.
As is well known, synchronizer clutches have blocker mechanisms, which permit synchronization of the input and output side of the synchronizer to be at a single speed prior to the shift being completed. The synchronizers have a collar or shift ring, which is manipulated by a shift fork. The fork is controlled by a rail, which is movable fore and aft relative to the vehicle by a shift lever. The transmission control has as many rails as is necessary to accommodate the synchronizers within the transmission. If three synchronizers are present, there will be three shift forks. Each of the rails includes a detent mechanism, which prevents movement of more than one shift rail at a time. Thus, each of the gears or synchronizers to be manipulated are operated in single fashion such that two synchronizers cannot be manipulated during one shift sequence. During the shift sequence, the outgoing synchronizer is moved to a neutral position prior to the oncoming synchronizer being moved to the operating position.
Planetary transmissions, on the other hand, employ fluid-operated torque-transmitting mechanisms such that the engagement of two or more operating control devices might be employed. In order to improve the efficiency of planetary transmissions, it is desirable and has been suggested that synchronizer-controlled torque-transmitting mechanisms be employed in the place of hydraulic devices. If the hydraulic device is removed, the high-pressure control pump is no longer needed to establish the engagement and disengagement of these devices such that a lower volume pump can be employed when the pump simply supplies lubricating fluid to the transmission in a manner similar to countershaft type manual transmissions.
It is an object of the present invention to provide an improved control mechanism for synchronizer torque-transmitting mechanisms used in planetary transmissions.
In one aspect of the present invention, a control member having a plurality of cam slots or spaces is employed to control the manipulation of synchronizer shift collars.
In another aspect of the present invention, the cam spaces are formed in a tubular member surrounding the planetary gearing and synchronizer torque-transmitting mechanisms of a power transmission.
In yet another aspect of the present invention, the tubular control member has an infinite radius thereby resembling a flat plate member.
In still another aspect of the present invention, the tubular control member is rotated to establish the desired selection and movement of the synchronizer torque-transmitting mechanisms.
In a further aspect of the present invention, the cam control mechanism is manipulated in an H-pattern by a conventional shift lever control.